- The system by which a :class:`.Column` considers itself to be an

"auto increment" column has been changed, such that autoincrement
is no longer implicitly enabled for a :class:`.Table` that has a
composite primary key.  In order to accommodate being able to enable
autoincrement for a composite PK member column while at the same time
maintaining SQLAlchemy's long standing behavior of enabling
implicit autoincrement for a single integer primary key, a third
state has been added to the :paramref:`.Column.autoincrement` parameter
``"auto"``, which is now the default. fixes #3216
- The MySQL dialect no longer generates an extra "KEY" directive when
generating CREATE TABLE DDL for a table using InnoDB with a
composite primary key with AUTO_INCREMENT on a column that isn't the
first column;  to overcome InnoDB's limitation here, the PRIMARY KEY
constraint is now generated with the AUTO_INCREMENT column placed
first in the list of columns.

1 files changed, 15 insertions, 0 deletions

diff --git a/test/sql/test_compiler.py b/test/sql/test_compiler.py
index c957b2f8a..f6f2ec740 100644
--- a/test/sql/test_compiler.py
+++ b/test/sql/test_compiler.py
@@ -2916,6 +2916,21 @@ class DDLTest(fixtures.TestBase, AssertsCompiledSQL):
             "CREATE TABLE t (x INTEGER, z INTEGER)"
         )
 
+    def test_composite_pk_constraint_autoinc_first(self):
+        m = MetaData()
+        t = Table(
+            't', m,
+            Column('a', Integer, primary_key=True),
+            Column('b', Integer, primary_key=True, autoincrement=True)
+        )
+        self.assert_compile(
+            schema.CreateTable(t),
+            "CREATE TABLE t ("
+            "a INTEGER NOT NULL, "
+            "b INTEGER NOT NULL, "
+            "PRIMARY KEY (b, a))"
+        )
+
 
 class InlineDefaultTest(fixtures.TestBase, AssertsCompiledSQL):
     __dialect__ = 'default'